﻿/************************************************************************

   Extended Silverlight Toolkit

   Copyright (C) 2010-2012 Xceed Software Inc.

   This program is provided to you under the terms of the Microsoft Public
   License (Ms-PL) as published at http://extendedsilverlight.codeplex.com/license

   Please purchase a commercial version of this toolkit if you are using
   it in a commercial product. The commercial versions support the project,
   and also include more features for each control, priority support,
   source code, updates, removed watermark, and a proprietary license.

   Visit http://xceed.com and follow @datagrid on Twitter.

  **********************************************************************/

using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Linq;

namespace Xceed.Silverlight.Data
{
  internal sealed class DataSourceSortContext
  {
    #region Constructors

    internal DataSourceSortContext( SortingHandler handler )
      : this( handler.SortDescriptions )
    {
    }

    private DataSourceSortContext()
    {
      m_readOnlySortDescriptions = new ReadOnlyObservableCollection<SortDescription>( m_sortDescriptions );
    }

    private DataSourceSortContext( DataSourceSortContext copy )
      : this( copy.SortDescriptions )
    {
    }

    private DataSourceSortContext( IEnumerable<SortDescription> sortDescriptions )
      : this()
    {
      foreach( SortDescription sortDescription in sortDescriptions )
      {
        m_sortDescriptions.Add( sortDescription );
      }
    }

    #endregion

    #region SortDescriptions Property

    internal IList<SortDescription> SortDescriptions
    {
      get
      {
        return m_readOnlySortDescriptions;
      }
    }

    private readonly ObservableCollection<SortDescription> m_sortDescriptions = new ObservableCollection<SortDescription>();
    private readonly ReadOnlyObservableCollection<SortDescription> m_readOnlySortDescriptions;

    #endregion

    public override int GetHashCode()
    {
      return this.SortDescriptions.Count;
    }

    public override bool Equals( object obj )
    {
      if( object.ReferenceEquals( obj, this ) )
        return true;

      DataSourceSortContext context = obj as DataSourceSortContext;

      if( object.ReferenceEquals( context, null ) )
        return false;

      if( context.GetHashCode() != this.GetHashCode() )
        return false;

      return context.SortDescriptions.SequenceEqual( this.SortDescriptions );
    }

    internal DataSourceSortContext Clone()
    {
      return new DataSourceSortContext( this );
    }
  }
}
